Hydrocarbons like crude oil are some of the most important energy sources worldwide. However, when these vital resources are spilled or are out of control, it causes significant environmental and ecological problems. For example, when crude oil is spilled in an aqueous environment, effective decontamination and cleanup are necessary for the protection of environment and human health. One important technology for mitigating crude oil spills is to apply a chemical herding agent that corrals the oil by reacting with water to reduce the air-water surface tension, which causes oil to retract or “push inward” from the periphery of the spill due to a negative spreading coefficient. This may be used to prevent a spill from spreading into a sensitive area, or to corral the oil into a thicker slick covering a smaller surface area. One such herding agent is the US Navy's (USN) cold water herder formulation (65% sorbitan monolaurate [Span-20] and 35% 2-ethyl butanol). Herding agents typically work most effectively when they are applied to undisturbed thin layers of oil slicks (<3 mm) for several hours. The objective is to create an oil slick thickness greater than approximately 3 mm, a thickness that allows the oil to be ignited and burned off. However, chemical herding agents suffer from several limitations. For example, they work best under calm sea conditions with low wind velocity and an absence of ice. Each application of a herding agent has a limited effectiveness of about an hour upon deployment. Furthermore, the herding agents themselves may be toxic.
Alternatives to herding agents can include sorbents. A sorbent acts by attracting and holding oil onto its surface; sorbents typically have highly interconnected pore spaces to increase the available surface area to increase the amount of oil that can be captured. An ideal sorbent rejects water (is hydrophobic) and is buoyant. After collecting oil, sorbents must then be retrieved and treated to recover, treat, or dispose of the oil. To facilitate retrieval, sorbents are formatted into sheets (for small spills typically in a confined area) or booms (for small to large spills, including open water spills). Mineral and synthetic sorbents can have high oil sorption capacity. However, they can be slow to degrade and/or can leave undesirable combustion products and are therefore not used with in situ burning. Vegetable-based sorbents are relatively friendlier to the environment, but do not perform as well, especially in the presence of waves and wind. They tend to have relatively low oil sorption capacity, low hydrophobicity and poor buoyancy compared to synthetic and mineral sorbents.
Accordingly, a need exists for oil adsorption materials that are environmentally friendly, have high oil sorption capacity, are highly buoyant, and can create oil slicks of sufficient thickness and stability (i.e., limited spreading, fragmenting, or sinking) to be burned in situ, even under windy, wavy, or icy conditions. A need also exists for methods of making the materials, and methods of using the material for environmental remediation.